Grounding is the process of electrically connecting conductive objects, such as electronic components, power generators and other electrical equipment, to an electrical ground for the purpose of safely completing either a normal or fault electrical circuit. An electrical ground may be any electrical conductor that is able to absorb a vast amount of electrical charge and therefore serve as an escape route for dangerous buildups of current. Thus, an accidental electrical surge will flow through electrical paths to the electrical ground rather than damaging the conductive objects.
Modern aircrafts are commonly designed to utilize composite materials to form component parts (such as panels, frames, stringers or stiffeners, skins, hulls, etc.) for use in fuselages, wings, tail assemblies and other aircraft structures, and to incorporate a variety of high tech electronic components, power generators and other electrical equipment that require an electrical ground path. Composite materials provide high strength and rigidity, low weight, corrosion resistance, fuel economy and other benefits, but do not provide conductivity needed for aircraft grounding, lightning strike protection or other electrical functions.
Additional electrical provisions are therefore installed in aircrafts made from composite materials to provide these functions. For example, typical ground/return systems in aircraft made from composite structures generally include one or more discrete, large-gauge electrical wires, or bundles of wires, that may run the entire length of an aircraft to provide an electrical ground or return path for leakage currents to flow from conductive objects to a sub-structure in the aircraft where it can be grounded. Metallic mesh (aluminum, copper or other metal) may also be placed on the outside of a composite lay-up on an aircraft's outer surface for lightning strike protection as described in commonly-owned U.S. Pat. No. 7,014,143. These additional electrical provisions effectively perform the required electrical functions, but they do not provide any structural benefits, may add weight to the aircraft, and may increase manufacturing time and cost.
It is therefore desirable for aircraft with composite component parts to have an electrical ground/return system that performs at least similar functions as known electrical ground/return systems while reducing the weight of, and the manufacturing time and material cost to produce, such an electrical ground/return system.